In order to elongate and relax a stud, a first part which is movable only in an axial direction engages the stud, a second part is connected with the first part, a friction element is connected with at least one of the parts radially inside the one part so that the first part has more surfaces cooperating with other elements than the second part, and then a holding force is applied to the friction element while an opposite active force is applied to the second part so that the second part is moved in the transverse direction and the first part is moved only in the axial direction to elongate the engaged stud.